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First Layer Calibration (i3)

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MMU family
MK3 family
MK3.5 family
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The First Layer Calibration is used to calibrate the distance between the tip of the nozzle and the print surface. The aim is to adjust the nozzle height until the extruded plastic sticks nicely to the bed and you can see that it is being slightly squished.

The printers assembled in the Prusa factory are already fine-tuned and this calibration is needed only in case you build the kit version at home or change the nozzle. The First Layer Calibration is part of the Wizard (last step of the XYZ-Calibration). You can also recalibrate the first layer later on from the LCD-menu - Calibration - First Layer Calibration. During this process, rotate the knob to manually adjust the distance between the nozzle and the bed, while the printer is printing a zig-zag pattern.

As each type of sheet (smooth, satin, and textured) has a different thickness you must use a different First layer calibration for each of them. For this, we have a convenient feature called Steel sheet profiles.

With a newly assembled printer, you will start at zero and move into a negative (-) value, reducing the distance between nozzle and heat bed. The initial zero-value is set by the P.I.N.D.A./SuperPINDA. position. Turn the knob counter-clockwise to bring the nozzle closer to the bed and moving the value away from zero. The value is unique to each printer and it may also slightly change with time and use. You must, therefore, check visually when adjusting the height, not by a set value. 

The first layer calibration being set incorrectly can lead to various issues. With the nozzle too far from the print surface, you risk your print not sticking properly, which can result in a blob. On the other side, if set too close, you can experience extrusion problems and clogging and poor print quality, or even damage to the hardware, like the Flexible steel sheet due to the print sticking too much. It is therefore important to get this right.

Before you proceed, make sure that the print surface (satin, smooth, or textured steel-sheet) is clean. You can find information on how to clean it in PEI print surface preparation. There are some small differences between how it should look on the textured and smooth steel sheet. We will, therefore, present pictures and guidelines for both, starting with the smooth sheet.

Turn the knob counter-clockwise to bring the nozzle closer to the bed.

Smooth sheet

Too high

You want the line flattened, but not squished. On the square at the end of the test line, you do not want any gaps between the lines (left picture), which means it is too high. In that case, the value will be too close to zero

Too low

If the nozzle is set too low (right picture) you will see the line squished completely flat and the end square will have ridges between the lines, which is a clear sign it is set too low and the value will be too far away from zero. When it is too low, the edges of the square can also start curling upwards. In the extreme, the filament will be spread so thin you will be able to see through the printed filament, leading to clogging of your hotend.

Having the nozzle too low can cause the nozzle to damage your steel sheet. This is not covered by Warranty.

Just right

A correct adjustment will show you an even surface (center picture), with no gaps between lines, nor ridges. As stated, the numeric value depends on the exact position of the P.I.N.D.A./SuperPINDA sensor, which will be unique to each machine and means nothing without a visual reference. However, a common range is from -0.400 to -1.500.

Adjusting it closer can in some cases improve adhesion. However, if you are having problems with adhesion, but your first layer calibration looks like the 'good' picture (center picture), your problem lies somewhere else, like a dirty/greasy sheet, print-settings, bed leveling/XYZ calibration, or under-extrusion.

You can not use the same first layer calibration if you swap between the Smooth and the textured sheet! For more information, please see Steel sheet profiles.

Textured sheet

The textured sheets are thinner than the sheets with smooth PEI, therefore you need to move the nozzle bit closer, but you are seeking the same results as with the smooth sheet. Again, if it is set too low (right picture) the filament can start curling up around the edges like it is not adhering. The numeric value will be too far from zero and must be adjusted back.

If set too high, you will see the line being round, and have gaps between the lines of the end-square. In this case, the value is too close to zero.

Have a look at the nozzle

A single layer is about 0.2 mm / 0.00787402 inch. Having a look at the nozzle and its distance to the sheet can also be helpful. However, measuring the printed layer with calipers is not a recommended method to calibrate the first layer.

When to run the First layer calibration

Generally, the first layer calibration should be performed every time there is a major change in the assembly. This includes changing the nozzle, extruder upgrades, or other updates to any axis. You should also run all calibrations if you move the printer to a different location.

For First Layer Calibrations with other nozzle diameters than 0.4 mm, please see this article

Other issues

  • If the width of the line varies across its length, you may have to do some Bed Level Correction.
  • If the nozzle comes in contact with the bed, the SuperPINDA/P.I.N.D.A. leveling sensor is not being triggered by the flexible steel sheet and must be physically moved lower in its holder. This will bring it closer to the level of the nozzle tip. You should make sure it is adjusted as instructed in the Preflight check in the Assembly manual. If you move the leveling sensor you must redo the First layer calibration.
 

87 comments

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wpla
I upgraded my MK4 to MK4S. When I ran the Fan diagnostics tests I noticed that the Fan Diagnostic test failed for the new MK4S Print Fan. After contacting the helpdesk they send me a new print fan, which failed also.  But then I disconnected the new MK4S Print Fan and connected the suspended MK4 print fan and ran the fan diagnostic test. It passed. Since I fooled the system with the suspended MK4 Print Fan I got my green check and I disconnected the MK4 print fan and reconnected the new MK4S Print Fan.
in this way I can normally upload a to be printed model again without confirming clicks on the printer during startup an uploading files.
the Helpdesk confirmed ne that is is a software glich which has to be addressed by Prusa. 
AsherSeitz
Hello, I have an mk3s+. when I am did first layer calibration, Turning the knob does not move the nozzle closer or further away from the bed. I have checked the wiring and it all looks correct. what should I do?
Jan Kratochvíl

Hello. Please contact our support team for help. Thank you.

Resosys
Hello, I made the first layer calibration on my MK3.5: on the right side of the steel sheet, the line thickness is good and sticks to the sheet but on the left side the line is too thin and doesn't stick, as if the mesh bed leveling data were not registered. Could you help me please. 
Dominik Sauer

Hello, you can try leveling the Z axis by moving the z axis all the way up. 


Orangedano
I have FW 3.13.1-6876 and have replaced pinda with super pinda.  I have done XYZ calibration sucessfully.  Now it says to do first layer calbiration.  When I try to do that, it asks if the filiment is loaded Y or N... clicking enter on either one does nothing.  I tried this both with the filiment loaded and unloaded.  (the IR sensor did pass its test).  HELP.
David B.

Hi! Is the filament sensor turned on in the menu?

Alid
I am having the same issue, but I cannot get the filament sensor to toggle off (it is stuck on but I do not think it is sensing either...).
I do not think the sensor is working because I ran out of filament the other day and I was not notified.
Orangedano
I reset the machine and now it is fine.
DavidG
help! I have lowered the nozzle as low as it can go and the first level print still doesn't blend the rows. I raise it and the space between the rows increases and really doesn't blend. what do I do?
Giuliano - Official Prusa CS
Hello. Perhaps the PINDA is too low. Check it's height and in case readjust it as illustrated in the final chapter of the assembly manual: https://help.prusa3d.com/guide/9-preflight-check_176167